Little chick is lethargic

The chick is 13 days old, and is a bantam. He is hunched over, tail down. When he chirps I hear a "popping" noise. He isn't eating, but I managed to get him to drink. He is having white and clear poops. I gave him some olive oil, probiotics and chick starter, all mixed together. He had a little poop on his vent, so I cleaned it of and rubbed some olive oil on that too. He is following my feet around, but walks like he's waddling. Yesterday was there first day outside, and he was good than
Any ideas?